We propose to continue and expand the clinical research and training programs of the Porphyrias Consortium (PC), a currently funded Consortium of the Rare Disease Clinical Research Network (RDCRN) that focuses on the inborn errors of heme biosynthesis, the porphyrias. The PC has brought together the complementary strengths of the senior porphyria experts at six regional centers; the American Porphyria Foundation (APF), the only US porphyria patient advocacy and support group; and biopharmaceutical companies interested in improving diagnosis and/or developing novel therapies for these diverse diseases. The Principal Investigator and Administrative Director will be Robert J. Desnick, PhD, MD, Icahn School of Medicine at Mount Sinai (MSSM) and Karl E. Anderson, MD, University of Texas Medical Branch, Galveston, respectively. The other four Consortium Directors are D. Montgomery Bissell, MD, University of California at San Francisco (UCSF); Joseph R. Bloomer, MD, University of Alabama at Birmingham (UAB); Herbert L. Bonkovsky, MD, Carolinas HealthCare System (CHS); and John Phillips, PhD, University of Utah (UoU). These porphyria experts form an interactive and interdisciplinary team of translational and clinical investigators who have active basic and clinical porphyria research programs, strong track records for training young investigators, and internationally recognized clinical expertise. For the past four years, they have worked as an effective team to accomplish the original objectives of the PC as documented in the progress reports for each project. The PC recruited over 450 patients in less than three years to the Longitudinal Study (LS) to document the natural history of each porphyria, and initiated six other clinical studies or trials, and a pilot/demonstration project. We will continue to enroll patients into the LS and other studies through the Contact Registry, APF and physician referrals, and the establishment of Outreach Clinics. In addition, we will continue training the next generation of porphyria experts, supported by $1.5 million in matching grants donated by patients and industry. New studies will focus on the acute hepatic porphyrias, including a project to identify safe new drugs and an in-depth observational study prior to clinical trials of Panhematin(r) and a novel RNA interference therapy. The pilot/demonstration program will include investigation of porphyria candidate modifier genes, Skype-based focus groups, and an exosome assay for hepatic ALAS1. These studies should lead to more effective management and treatment of these diseases.